Photographic silver halide emulsions

ABSTRACT

Green sensitized silver chlorobromide emulsions containing a Jband sensitization type dye are improved by adding specific amounts of a water soluble iodide or bromide to the emulsion.

United States Patent Shiba et al.

[ Feb. 11, 1975 PHOTOGRAPHIC SILVER HALIDE EMULSIONS Inventors: KeisukeShiba; Masanao Hinata;

Hiroyuki Amano; Hiroshi Hara, all of Kanagawa, Japan Fuji Photo FilmCo., Ltd., Kanagawa, Japan Filed: Nov. 10, 1971 Appl. No.: 197,398

Assignee:

Foreign Application Priority Data References Cited UNITED STATES PATENTSJones 96/125 Jones 96/125 Jones 96/125 lllingsworth 96/ 108 Philippaertset a1. 96/94 lllingsworth 96/94 R McNamara 96/94 R PrimaryExaminer-Norman G. Torchin Assistant Examiner-Richard L. SchillingAttorney, Agent, or Firm--Sughrue, Rothwell, Mion, Zinn & MacPeakABSTRACT Green sensitized silver chlorobromide emulsions containing aJ-band sensitization type dye are improved by adding specific amounts ofa water soluble iodide or bromide to the emulsion.

12 Claims, 1 Drawing Figure Z so- 2 5 40,

400 500 600 100 WAVELENGTH (nm) P/KTEHTED F551 1 1975 3; 865,598

PERCENT TRANSMISSION 400 560 600 760 WAVELENGTH (nm) 1 PIIOTOGRAPHICSILVER I-IALIDE EMULSIONS BACKGROUND OF THE INVENTION l. Field of theInvention The present invention relates to photographic silver halideemulsions. In more detail, the present invention relates to silverhalide emulsions containing a .l-band sensitization type dye, andespecially to an improvement in silver halide emulsions containing aJ-band sensitization type dye suitable for green sensitization.

2. Description of the Prior Art It is known, e.g., see F. M. Hamer:Cyanine dyes and related Compounds; 710 (1964) (published byInterscience), that sensitization maximums by various sensitizing dyesis silver halide emulsions (M-band sensitization maximums by molecularabsorption) are in a slightly longer wavelength than the absorptionmaximum of the dye in an aqueous solution, but are very close.

Certain kinds of sensitizing dyes show a sharp sensitization band at asomewhat longer wavelength (approximately 50 mm) than the M-bandsensitization maximum wavelength. This phenomenon is known as J-bandsensitization. Hereinafter, sensitizing dyes which show J-bandsensitization refers to .l-band sensitization type dyes.

In general, photographic sensitizing dyes are divided into those whichprovide effective M-band sensitization in silver halide emulsions andthose which provide effective .I-band sensitization. There are manykinds of dyes which show J-band sensitization. Since it is very tediousto describe the chemical structures thereof one by one, these dyes aredescribed hereinafter as J-band sensitization type dyes.

It is well known that the intensity of the .l-band sensitization isinfluenced by the chemical structure of the sensitizing dye and thecharacteristics of the emulsions, for example, the composition of thesilver halide, the crystal form of silver halide, the silver ionconcentration in the emulsion and the pH. Furthermore, the intensity ofthe J-band sensitization is affected by segmentation agents,stabilizers, coating aids or couplers coexisting in the emulsion. Inmany cases, compounds other than .l-band sensitization type dyes addedto the emulsion function to weaken J-band sensitization.

The present invention, deals with comparatively high contrast (ie highy-value) sensitive elements, namely those except low contrast sensitiveelements, having a comparatively high sensitivity. Such sensitiveelements include, for example, black and white printing sensitiveelements (monochromatic printing paper), color printing sensitiveelements (for example, color printing paper and color positive film),high contrast sensitive elements for copying, sensitive elements forprinting plates and high contrast sensitive elements for televisions.

It is well known that silver halide emulsions with a green-sensitivelayer and a red-sensitive layer in a color photographic multi-layerelement are used after spectral sensitizing. It is also known that theuse of the following layer arrangement which improves sharpness isprefered for the color multi-layer elements, especially color printingmulti-layer sensitive elements and particularly color positive films: Ablue sensitive layer is situated adjacent to a support; agreen-sensitive layer and a red-sensitive layer having a substantiallylower sensitivity than that of the blue-sensitive layer are coated LIIthereover; each sensitive silver halide layer contains a color couplerwhich forms an image having a complementray color to the sensitivity ofthe multilayers. In this case, the blue-sensitivity of the greensensitive layer is lower than the blue sensitivity of the bluesensitivelayer, though it is similar to that of the red sensitive layer (incommon color paper or color positive films, the blue sensitivity of thegreen-sensitive layer is one-tenth or so of that of the blue sensitivelayer).

In color printing sensitive elements, it is usually necessary to obtainhigh contrast images with low fog and stain. Considering theserequirements, an AgBrl emulsion and a silver chloride emulsion are notsuitable as silver halide emulsions for the green sensitive layer. Thesilver iodide bromide emulsion has a low developing rate and a lowcontrast as compared with a silver chloride emulsion or a silverchloride bromide emulsion. Besides the preparation of a silver iodidebromide emulsion require a long washing step prior to chemical ripening(or second ripening) because chemical ripening is difficult without longwashing. On the other hand, a silver chloride emulsion has the faultthat develop ment proceeds too rapidly and the emulsion is easily foggedas compared with the silver chloride bromide emulsion. Accordingly, thesilver chloride bromide emulsion is more prefered in a printingsensitive elements.

It is also known that the spectral sensitization of a green sensitivelayer of a color multilayer element is advantageously carried out usingJ-band sensitization sence selective sensitization is afforded thereto..l-band sensitization is effective in the green sensitive layer of thecolor printing sensitive element to provide good color separation andgood processing under a safelight.

In color printing sensitive elements and black and white sensitiveelements, strict standards are required for residual colors caused bythe sensitizing dyes, stains and fogs.

Though the silver chloride bromide emulsion is advantageous for highcontrast sensitive elemtnts, especially the printing sensitive element,because of its rate of development, fog and gradation as describedabove, it has the fault that J-band sensitization thereof is difficultwith .Lband sensitization type dyes.

Many attempts have been made to remove this fault, e.g., many supersensitizing agents for intensifying J- band sensitization have beenexamined. However, good effects are barely observed in dyes which areuseful for intensifying J-band sensitization. For example, a cyanine dyehaving the following formula (which is not a quaternary salt if itcoexists with color couplers) is little improved by supersensitizingagents.

l CH5 by the dye is large.

an O U o G N a G,

1 (CH so" 2 4 3 (CH )4SO H It is known that the J-band sensitization'ofstreptocyanine dyes is strengthened by adding potassium iodide orpotassium bromide to the silver chloride bromide emulsion, i.e., seePhoto. Sci. Eng, 13(1) 13 17. However, the streptocyanine dyes describedin the above-mentioned literature are for sensitizing to wavelength ofless than 500 mm, and are not suitable for sensitization of the greensensitive range. Moreover, by addition of potassium iodide or potassiumbromide while the .l-band sensitization is strengthened, gradation andlow contrast suffer and fog is caused. Further, the stability of theemulsions in which potassium iodide or potassium bromide is addeddeteriorates with lapse of time. Especially, with potassium iodide thesensitivity deteriorates with time.

SUMMARY OF THE INVENTION It is the principal object of the presentinvention to provide'a green sensitized photographic silver halideemulsion containing J-band sensitization type dyes, wherein low contrastthereof is not encountered by the addition of a water soluble iodideand/or water soluble bromide. 1 I

Another objectof the invention is to provide a sensitive element withan. emulsion layer which does not suffer from lowering of thesensitivity thereof during the passage of time.

These and other objects of the present invention are accomplished byincorporating in a silver chlorobromide emulsion, to increase the.I-band sensitization thereof, a water soluble iodide and/or a watersoluble bromide. As an example the J-band sensitization isadvantageously increased by adding a water soluble iodide or a watersoluble bromide to a silver chloride bromide emulsion containing aJ-band sensitization type dye in an amount of 0.005 0.10 moles of thewater soluble iodide per mole of the silver chloride component in thesilver chloride bromide emulsion. The I/AgCl (molar ratio) and 0.01 0.20moles of water soluble bromide per one mole of the silver chloridecomponent The Br'/AgCl (molar ratio).

The low contrast is not brought about by the addition of the watersoluble iodide or water soluble bromide and lowering of the sensitivityof the silver halide sensitive element composed of said emulsion layersis scarcely observed with passage of time.

When the l/AgCl molar ratio is less than 0.005 or the Br/AgCl molarratio is less than 0.01, though the J-band sensitization isstrengthened, its effect is small. Moreover, lowering of sensitivitywith time is large.

On the other hand, when theF/AgCl 'molar ratio is higher than 0.10 orthe Br/AgCl molar ratio is more than 0.20, the gradation of thesensitive element composed of the emulsion layers yields low contrastand the lowering of the sensitivity with time becomes large, though.I-band sensitization is seen.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a spectral transmittancecurve ofa filter.

DETAILED DESCRIPTION OF THE INVENTION In order to attain the objects ofthe present invention, the time of addition of the water soluble iodideor water soluble bromide is a particularly important matter, i.e., it iseffective to add them to the emulsion not prior to substantialcompletion of chemical ripening and especiallyprefered to addthem aftersubstantial completion of chemical ripening to be followed by theaddition of sensitizing dyes. On the other hand, if they are addedmarely after conclusion of the physical ripening, but during chemicalripening, the sensitive element has a low contrast, though the J-bandsensitization is strengthened, and consequently it is difficult'to use.

Either the water soluble iodide or the water soluble bromide thewater-solubility of which is greater than 10 mol/l can be used in thepresent invention. Typical water soluble salts used include iodides andbromides of ammine, alkalimetal and alkaliearth metal such as ammonium,potassium, lithium, sodium, cadmium and strontium.

The amount of AgBr in the preferred photographic emulsions of the highcontrast sensitive element is from about 15 to about 95% and preferablyfrom 30 to (molar values).

The particle size of the silver halide used in the silver chloridebromide emulsions used of the present invention is not limited and canbe of a-size within ranges used in common prior art photographicemulsions. However, an average particle size by number less than 0.6 ,uis especially prefered for use in high contrast sensitive elements.Asthe silver halide particles, regular particles, i.e. particleshavingno twin planes, and/or irregular particles may be used. However,regular particles are more effective in the present invention. Further,though emulsions which are not monodispersed may be used in the presentinvention, monodispersed emulsions are preferably used.

The J-band sensitization is increased by adding the water soluble iodideor the water soluble bromide to silver chloride bromide emulsionscontaining a J-band sensitizing type dye in the above-mentioned amount.Not only does the sensitivity increase in an unexpectedly high degreeremain high with the passage of time, but the following characteristicsare also provided.

It is possible to lower residual coloring after treatment of thesensitive element composed of emulsions containing .l-band sensitizationdyes since sufficient J- band sensitization is obtained by adding asmall amount of the J-band sensitization dyes to the emulsions in viewof the unexpected great increase of the J-band sensitization.

By strengthening the J-band sensitization, green sensitzed emulsionswhich show little lowering of sensitivity in the presence of colorcouplers can be obtained,

i 6 which final special use for the green sensitization of acetoxylgroup etc., carbalkoxy group, e. g., carbethoxy color print sensitiveelements. group etc., or alkoxycarbonylamino group, e.g., ethox-Additives used for improving the physical properties ycarbonylaminogroup etc; of gelatin emulsion films, for example, vinyl polymer Y and Ycan each represent a hydrogen atom, lower dispersions produced by usingan anionic surface active 5 alkyl group, e.g., methyl group, ethyl groupetc., haloagent, as are known from British Pat. No. 1,186,699 gen atom,e.g., chlorine atom, bromine atom, fluorine etc., formerly function tointerrupt J-band sensitizam etc., hydroxyl group, alkoxy groupfi-gmethoxy tion. However, in the present invention, the .l-bandsengroup of ethoxy group, amino group, e.g., amino group sitization ofemulsions containing the water soluble ioan m hyl mino group, acylamidogroup, e.g., acetdide or water soluble bromide is hardly affected by 10amido group etc., acyloxyl group, e.g., acetoxyl group thesedispersions. etc., carbalkoxy group, e.g., carbethoxy group etc., al-

Compounds used as flocculating agents are known, koxycarbonylaminogroup, ethoxycarbonylamino for example, from Jap. pat. Pub. No.Sho.40-2747O group -i or the P y p; (Dec. 3, 1965) a US. Pat. No.2,489,341 and British Yaand e n each representa y g atom. or 3 Pat. No.1,135,622. These flocculating agents usually can represent a group ofatoms necessary to form a interrupt J-band sensitization. The J-bandsensitization benzene ring by linking to 2 and e can represent a ofemulsions containing the water soluble iodide or g p f a oms necessaryto form a benzene ring by water soluble bromide used in the presentinvention is linking to 5- hardly affected by these flocculating agents.2 and 1 and 5 and 4 each y fOI'm a ene ring, with the proviso that bothof Yg-Yg and Y- -Y, each do not form a benzene ring at the same time andwith proviso that the further both of Y Y and Y Y each do not form abenzene ring at the same time;

R, and R can each represent an alkyl group e.g. methyl group, ethylgroup, n-propyl group etc., a substituted alkyl group conventionallyemployed inthe cy- Compounds used as fog inhibitors or stabilizers suchas benzotriazole, nitrobenzimidazole, 5-nitroimidazole, mercaptans and5-methyl-7-hydorxyl ,34- triazaindolizine usually function to interrupt.l-band sensitization. However, the J-band sensitization of emulsionscontaining the water soluble iodide or water soluble bromide used in thepresent invention is hardly I a I I uffecwd y these compoufids antne dyesensitizing art, e.g., hydroxyalkyl group, c.g.

Z-hydroxyethyl group, 4-hydroxybutyl group etc., acc- Azo dyes used forsliver-dye bleaching methods as toxyalkyl group, mg zacetoxycthyl group3 described in Jap. Pat. Pub. No. Sho 36:10280, Sho oxypropyl groupetc., alkoxyalkyl group, e.g. 2- 39-9587 and Sho 39-25768 usuallyfunction to mtermethoxyethyl group, 44mm, butyl group etc, a cap ruptJ-band sensitization H owever, the J-band sensiti boxy group containingalkyl group, eg zncarboxyethyl zation of emulsions containing the watersoluble iod de group, 3-carboxypropyl group, 2-(2carboxyethoxor watersoluble bromide used in the present invention wethyl group etc a sum)group Containing an alkyl hardly affected by these azo dyes group, e.g.,2-sulfoethyl group, 3-sulfopropyl group, 3

Any dye which exhibits J-band sensitization can be sulfobutyl group,4-sulfobutyl group, 2'hydroxy-l effectively used in the presentinvention. J-band sensitisulfopropyl group, 2-(3-sulfopropoxy)ethylgroup, zation type dyes suitable for green sensitization mostZ-acetoxy-l-sulfopropyl group, 3-methoxy-2-(3-sulfopreferably used inthe present invention have the folpropoxy)propyl group,2-(2-(3-sulfopropoxy)ethoxlowing formulae (1), (11), (111), (IV), (V),and (V1): y)ethyl group, 2-hydroxy-3-(3'-sulfopropoxy)propyl Y O O Y=CH-C CH Y N 11 Y- wherein R represents a hydrogen atom or lower alkylgroup, etc., a benzyl group, a phenylethyl group, a pgroup, e.g., methylgroup or ethyl group; sulfobenzyl group, p-carboxybenzyl group, a p- Y,and Y, can each represent a hydrogen atom, a sulfophenethyl group, or anallyl group; at least one of lower alkyl group, e.g., methyl group orethyl group, R1 and R being a carboxyl group containing alkyl halogenatom, e.g., chlorine atom or bromine atom g p or a sulfo gr p containingalkyl g p; etc hydrgxy] group, alkoxy] group alkoxy] group e g Xrepresents an anion .g. ChlOlldE, bromide, iodide, methoxy group orethoxy group etc., amino group, e.g., thiochanate, sulfonate,perchlorate, p-toluenesulfonamino group or methylamino group etc.,acylamino ate, methylsulfonate and ethyl sulfate etc;

group, e.g., acetamide group etc., acyloxy group, e.g., n represent 1 or2.

R a (II) =CHCH=C1I v Y8 T lO i 2 tl (X n-l wherein Z represents-O-orgroup, etc., carboxyl group, alkoxycarbonyl group, R e.g.,methoxycarbonyl group, ethoxycarbonyl group, 4 etc., cyano group ortrifluoromethyl group; Y represents a hydrogen atom or a group of atoms5 necessary to form a benzene ring together with Y,,,;

Y and Y may form a benzene ring with the proviso wherein R and R eachrepresent an alkyl group prefthat both of Y -Y and Y -Y each do notforin a benerably having upto 4 carbon atoms e.g. methyl group, zenering at the same time; ethyl group, etc.; R,,R ,X and n each can havethe same meaning as in R represents a lower alkyl group, e.g. methylgroup, formula (I).

e R ,3 (III) g I 5 I Y Y N =CHCH=CH Y N Y ethyl group, etc., or an allylgroup; Wherein, R and R each can represent an alkyl Y, represents ahydrogen atom or halogen atom, e.g., group e.g. methyl group, ethylgroup, propyl group, chlorine atom, bromine atom, fluorine atom; butylgroup, etc., Y and Y represent a hydrogen Y; represents a hydrogen atomhalogen atom, e.g., atom or halogen atom e.g., chlorine atom, brominechlorine atom, bromine atom, fluorine atom, etc., alkatom, iodine atom,fluorine atom; oxy group, e.g., methoxy group, ethoxy group, etc., Y,;,and Y each represent a hydrogen atom, halogen amino group, e.g., aminogroup, methyl amino group, atom, e.g., chlorine atom, bromine atom,iodine atom etc., acylamido group, e.g., acetamido group, etc., andfluorine atom, an alkoxy g p, -g-, m h y acyloxy group, e.g., acetoxygroup, etc., or alkoxycargr p, xy gr p, butoxy g p an amino bonylaminogroup, e.g., ethoxycarbonylamino group, group, e.g., amino group, methylamino group, dimethetc; 5O ylamino group, etc., an acylamido group,e.g., an acet- Y,; represents a hydrogen group, a lower alkyl group,amido group etc., an acyloxy group c.g. acetoxy group e.g., methylgroup, ethyl group, etc., halogen atom, etc., an alkoxycarbonylaminogroup, e.g., ethoxycare.g., chlorine atom, bromine atom, etc., ahydroxy] bonylamino group,ctc., acyano group, trifluoromethyl group, oran alkoxy group, e.g., methoxy group, ethoxy group, alkyl sulfonylgroup, e.g., methylsulfonyl group, group, etc. etc., a sulfomyl group,alkylaminosulfonyl group, e.g., Y represents a hydrogen atom, a loweralkyl group, ethylaminosulfonyl group diethylaminosulfonyl group, e.g.,methyl group, ethyl group etc., halogen atom e.g., etc., amorpholinosulfonyl group, or pyperidinosulfonyl chlorine atom, bromineatom, fluorine atom, etc., an group, etc.; alkoxy group, e.g., methoxygroup, ethoxy group, etc., R R X and n each have the same meaning as inforthe phenyl group, e.g. phenyl group, p-sulfophenyl mula (I).

O 16 3% l l =cH-c- 1? I N l8 l wherein, R represents a hydrogen atom ora lower oxy group, etc., or a halogen atom, e.g., chlorine atom, alkylgroup eg., methyl group, ethyl group, etc.; Y, bromine atom, etc;represents a hydrogen atom, a halogen atom, eg., chlo- R R X and n eachhave the same meaning as in forrine atom etc., or a lower alkyl group,e.g., methyl mula (1). group, ethyl group, etc., Y represents a hydrogen5 Merocyanine dyes as referred to in C. K. Mees,The atom, a halogenatom, e.g., chlorine atom etc., an alkyl Theory of The PhotographicProcess, Revised Edigroup eg., methyl group, ethyl group, propyl group,tion, pp,445, lines 9 to 10 up may be also employed in etc., an alkoxygroup, eg., methoxy group, ethoxy the present invention. Dye representedby Formula (I) group, phenyl group etc.; Y represents a hydrogen and(111) are described in French Pat. No. 1,108,788 atom or a group ofatoms necessary to form a benzene 10 (Sept. 14, 1955), US. Pat. No.2,503,776 (Apr. 11, ring together with Y ;Y, and Y each represent a hy-1950), US. Pat. No. 2,912,329 (Nov. 10, 1959) and drogen atom; a halogenatom, eg., chlorine atom, bro- US. Pat. No. 3,397,060, and can easily besynthetized mine atom, etc., a lower alkyl group, eg., methyl by personsskilled in the art with reference to the group, ethyl group, etc., or analkoxy group, eg., methabove-mentioned patent specifications or bymethods oxy group, ethoxy group etc,; 15 similar to those described inthose patent specifica- R,, R X and n each can have the same meaning asnous, in formula (1). Dyes represented by the formula (II) are describedin Wherein Y represents a hydrogen atom, hydroxyl US. Pat. No. 3,364,031(Jan. 16, 1968), and lap. Pat. group, a lower alkyl group, eg., methylgroup, ethyl Pub. No. Sho 44-14030 (Jan. 18, 1966), dyes repregroup,etc., a halogen atom, e.g., chlorine atom, etc., sented by the formula(IV) are described in Jap. Pat. or an alkoxy group, eg., methoxy group,ethoxy group, Pub. No. Sho 43-16169, dyes represented by the foretc; Yrepresents a hydrogen atom, a lower alkyl mula (V) are described in WestGermany Offengroup, eg., methyl group, ethyl group, etc.; Yreprelegungsschrift No. 1,936,262 (July 16, 1968), and dyes sents ahydrogen atom, a lower alkyl group, eg., methyl represented by theformula (VI) are described in West group, ethyl group, etc.; an alkoxygroup, eg., methoxy Germany Offenlegungsschrift No. 2,014,896 and cangroup, etc.; a hydroxy group, or a phenyl group; easily be synthetizedby persons skilled in the art with wherein Z represents an atomic groupnecessary to reference to the above-mentioned patent specification,

complete a S-membered heterocyclic ring; or by methods similar to thosedescribed in said pa- R,, R X and n each have the same meaning as infortents.

mula (U- The following are specific examples of J-band sensi- Wherein Yand Y each represent a hydrogen tizing dyes used in the presentinvention, but the sensiatom, a lower alkyl group, e.g., methyl group,ethyl tizing dyes used in the present invention should not be group,etc., an alkoxy group, eg., methoxy group, ethconsidered as limitedthereto.

Dye 16 Dye 19 Dye 20 21 22 Dye fi l H30 S CH3 ==CH- N t I on 2 5 (cu s1? N OH 2 5 (cH so Dye 3 6 :CH- N I N CH (CH2)3SO3H Zhl- "T3 V N l (ons0 (CH SO lI-N(C I1 The sensitizing dyes are preferably used in anamount of 0.005 2.0g/(per one gram mole of silver halide) in the presentinventionflhe addition of the sensitizing dyes to emulsions is carriedout by methods well-known in this field. Usually, they are added as anaqueous solution or as a solution in organic solvents such as methanoland ethanol. Further, water insoluble sensitizing dyes as described inBritish Pat. No. 1,154,781 can be added as a dispersion in an aqueouscolloid.

1n the present invention, a gelatin silver halide emulsion is usuallyused. However, other hydrophilic binders such as resinous materials andcellulose derivatives which do not have a harmful influence upon thesensitive material can be used instead of gelatin.

The photographic emulsions used in the present invention may include achemical sensitizing agent, a fog inhibitor, a stabilizer, a hardeningagent, a coating assistant, a plasticizer, a development accelerator, anair fog inhibitor, color couplers, etc.

The photographic emulsions may be applied to any suitable support suchas glass, films or cellulose derivatives, synthetic resin films,synthetic papers, baryta -CCH CONH NHCOCH -O C H t) 00H C H (t) EXAMPLESl 3 Metol 0.3l g Anhydrous sodium sulfite 39.6 g A sensitizing dye wasadded to an emulsion prepared gyg -z q b 3 8 3 by the followingformulation, and after substantial g fi fjlfi ig 'ffi car on e 86 gcompletion of chemical ripening. Then, after adding as Is Citric acid gaqueous solution of potassium iodide, the resulting i metab'summ fimixture was applied to a cellulose triacetate base. Preparation andformul i of at on emulsion After fixing, washing and drying, the opticaldensity was determined with a desensitometer. The results Gelatin g 20were shown in Table l. The sensitizing dye used was Sodium Chloride gDye l, which was added in the amount of ml per kg Water 800 ml H Silvernitrate 100g of the emulsion as a methanol solution having a 10 Water60( ml mols/liter concentration.

Table 1 Example Amount of l l/AgCl Yellow sensitivity No. per gram atom(molar (relative value) of silver ratio) Just after After 5 daysapplication at 40C and 80 70 relative humidity Comparison 0 0 100 250.00118 0.00169 I38 29.5 0.00236 0.00337 407 l20 1 0.00353 0.00500 2040l290 2 0.00706 0.0l085 2520 2000 3 0.01 l80 0.0l690 2700 2150Potqssiumhlbrqmide 5;: From Table 1 it can be seen that sensitivityincreases $5.12? C onde fiod l remarkably when the l/AgCl ratio is above0.005 and W W aqueous Sodium carbonate the sensitivity lowers by only asmall degree with time.

solution 7.0 ml Water 1600 ml EXAMPLES 4 6 V Gelatin I80 g A sensitizingdye was added to an emulsion prepared l i 1] d S l i I" were dd d at hsame with the following formulation after substantial comtime toSolution l at 60C over a 20 minute period. Pleticm chemical p g- The",aftefiaddmg Cdlz, After ripening at 60C for 5 minutes, the temperat theemulslon was applled to a cellulose triacetate base. was brought down to40C, and dilute sulfuric acid was Preparauon and formulatlo" ofemulslon: added so as to lower the pH (to about pH 3.5 4). After addinga floculating agent, Nekal A and washl Gelatin 20 g ing, Solution IV andthen Solution V were added, and Sodium chloride L0 g Water 800 ml thesilver halide was dispe rsed again. The resultmg Silver mm 100 gemulsion was r pened at 55 C till it reached optimum water 600 ml l lllPotassium bromide 35 g sensitivity (about minutes) (chemica ripening) 60Sodium chloride 83 g e coated samples were dried and exposed throughwater 600 m1 a Fu i K filter No. 3 (trade mark) and a light wedge for IV1N agueous sodium carbonate 7 one second using a tungsten lamp as thelight source. The FUJI K filter No. 3 IS a yellow filter which passes vGelatin 180 g rays of above approximately 5 l0 nm. The exposed sampleswere developed at 20C for 4 minutes using the following developingsolution. Formulation of developing solution:

The conditions for preparing the emulsion were the same as for Examples1 3, and the condition of exposure and treatment were the same as inExamples 1 3. The sensitizing dye used was Dye 8, which was added in anamount of 80 ml per Kg of the emulsion as a methanol solution having a10 mols/literconcenti'ation. The results of measurements as in Example 1are shown in Table 2.

Table 2 wedge for 2 seconds using a tungsten lamp as the light -source.Th.e Fuji K filter No. 17 is a green filter having the transmittanceshown in the drawing. After exposure, the samples were color-developedusing a color developing solution and then they were treated in turnExample Amount of 1 1'/AgCl Yellow sensitivity No. per gram (molar(relative value) atom of ratio) Just after After 5 days at silverapplication 40C and 80% re,-

7 lative humidity Comparison 0 100 52 0.00118 0.00236 316 63 0.002360.00472 830 199 4 0.00471 0.00942 1000 830 5 0.00706 0.01412 1120 1 1206 0.00942 0.01884 1150 912 From Table 2 it also can be seen thatsensitivity increases remarkably when the F/AgCl ratio is above 0.005and the sensitivity lowers by only a small degree with time.

EXAMPLES 7 '11 A sensitizing dye was added to an emulsion prepared withthe following formulation after substantial completion of chemicalripening. Then, after adding [(1 or KBr, a dispersion of coupler*, ahardening agent and a coating assistant were added thereto, and themixture was then applied to baryta paper. Preparation and formulation ofemulsion:

l Gelatin Sodium chloride 1.0 g Water 800 ml 11 Silver nitrate 100 gWater 600 ml 111 Potassium bromide 49 g Sodium chloride 12 3 Water 600ml 1V 1N aqueous sodium carbonate solution 7.0 ml Water 1600 ml VGelatin 180 g "Coupler (12) was used as the coupler.

Other conditions for preparing the emulsion were the same as in Examples1 3.

The coated materials were dried and exposed through a Fuji K filter No.17(trade mark) and a light by the following treatments; fixing, washing,bleaching,

washing, hardening, washing, stabilizing. The optical density of thetreated samples was determined with a desensitometer. The results areshown in Table 3. The

sensitizing dye used was dye 1 6, which was added in the amount of mlper Kg of the emulsionas a methanol solution having a 10' mols/lite-rconcentration.

(Formula of a color developing solution) Sodium methaborate Sodiumsulfite hydroxylamine (sulfate) potassium bromide 6-nitrobenzimidazole(nitrate) sodium hydroxide benzylalcohol diethylglycol N-ethy1-N,fi-(methanesult'oamideethyl)-phenylene diammine ater to make 1.

neoermua 0Q liter (pH 10.6)

From Table 3 it'also can be seen that sensitivity increases remarkablywhen the llAgCl ratio and the Br /AgCl is above 0.005 and 0.01,respectively and the sensitivity lowers by only a small degree withtime.

Table 3 EXAMPLES 12 19 A sensitizing dye was added to an emulsionprepared with the following formulation after substantial completion ofchemical ripening. Then, after adding Kl, a dispersion of a coupler* ahardening agent and a coating aid were added thereto, and then themixture was applied to a polyethylene coated paper base. Coupler (l) wasused as the coupler.

that sensitivity increases remarkably when the llAgCl ratio is above0.005 and no greater than 0.l and the sensitivity loweres by only asmall degree with time.

What is claimed is: v I

1. In a photographic silver halide emulsion greensensitized by at leastone J-band sensitization type trimethine cyanine dye, wherein at leastone of the ni' trogen containing heterocyclic nuclei of said dye has, onthe nitrogen atom thereof, a RCOOH group wherein R is an alkylene group,or a sulfoalkyl group, the improvement wherein said .l-bandsensitization type dye is present in a binder dispersion of silverclorobromide containing a water soluble iodide in a molar ratio 15 of0.005-0.l0, based upon silver chloride which is a of I):

General Formula (I) Other conditions of preparing the emulsion were thesame as in Example 1 3.

Coated samples were dried and exposed through a Fuji K filter No. 17 andalight wedge for one-millionth ofa second using a Mark Vll sensitometerproduced by EG & G Co. (U.S.A.). After exposure the samples werecolor-developed using a color developing solution, and then they weretreated by the following treatments in turn:, fixing, washing,bleaching, washing, hardening, washing and stabilizing. The opticaldensity of the treated samples was determined with a desensitometer. Theresults are shown in Table 4. The sensitizing dye used was Dye 2, whichwas added in the amount of 40 ml per Kg of the emulsion as a methanolsolution having a 10 mols/liter concentration.

Table 4 R represents a hydrogen atom or lower alkyl group, Y and Y eachrepresent a hydrogen atom, lower alkyl group, halogen atom, hydroxylgroup, alkoxyl group, amino group, acylamino group, acyloxy group,carboalkoxy group, or alkoxycarbonylamino group;

Y and Y each represent a hydrogen atom, lower alkyl group, halogen atom,hydroxyl group, alkoxy group, amino group, acylami 0 group, acyloxylgroup, carbalkoxy group, alkoxycarbonylamino group, or the phenyl group;

Y and Y each represent a hydrogen atom, or Y can represent a group ofatoms necessary to form a benzene ring by linking to Y and Y canrepresent The color developing solution has the same formula as inExamples 7 to l l. From Table 4 it can also be seen a group of atomsnecessary to from a benzene ring by linking to Y;,;

Y and Y and Y and Y each may form a benzene ring with the proviso thatboth of Y -Y and Y -Y each do not form.a benzene ring at the same timeand with the further proviso that both of Y -Y and Y -Y each do not forma benzene ring at the same time;

R and R each represent an alkyl group or a substituted alkyl groupconventionally employed in the cyanine dye-sensitizing art, at least oneof R and Y represents a hydrogen group, a lower alkyl group, halogenatom, a hydroxyl group, or an alkoxy group;

Y represents a hydrogen atom, a'lower alkyl group,

5 halogen atom, an alkoxy group the phenyl group, carboxyl group, alkoxycarbonyl group, cyano group, or trifluoromethyl group,

Y represents a hydrogen atom or a group of atoms necessary to forma'benzene ring together with Y R being a RCO0H group h i R i amylene l0Y and Y may form abenzene ring with proviso that or a sulfoalkyl groupboth of Y -Y and Y -Y each do not form a ben- X re resents an anion zenering at the same time; I

p 7 R R X and n each have the same meaning as in forand n represents 1or 2: mula (I):

General Formula II -CHCH=CH- I Y \N N I i Y 1o R R General Formulawherein Z represents --O or ,5 wherein R and R each represent an alkylgroup;

R represents a lower alkyl group or an ally! group;

Y, represents a hydrogen atom or halogen atom;

Y represents a hydrogen atom, halogen atom, alkoxy group, amino group,acylamido group, acetoxy group, or alkoxycarbonyl amino group;

General Formula bonylamine group, a cyano group, trifluoromethyl group,alkyl sulfonyl group, a sulfamyl group, alkylaminosulfonyl group, amorpholinosulfonyl group, or pyperidinosulfonyl group;

R R X and n each have the same meaning as in formula (l):

:CH-C=CH-

1. IN A PHOTOGRAPHIC SILVER HALIDE EMULSION GREEN-SENSITIZED BY AT LEASTONE J-BAND SENSTIZATION TYPE TRIMETHINE CYANINE DYE, WHEREIN AT LEASTONE OF THE NITROGEN CONTAINING HETEROCYCLIC NUCLEI OF SAID DYE HAS, ONTHE NITROGEN ATOM THEREOF, A -RCOOH GROUP WHEREIN R IS AN ALKYLENEGROUP, OR A SULFONALKYL GROUP, THE IMPROVEMENT WHEREIN SAID J-BANDSENSITIZATION TYPE DYE IS PRESENT IN A BINDER DISPERSION OF SILVERCLOROBROMIDE CONTAINING A WATER SOLUBLE IODIDE IN A MOLAR RATIO FO0.005-0.01, BASED UPON SILVER CHLORIDE WHICH IS A COMPONENT OF SAIDSILVER CHLOROBROMIDE.
 2. A photographic silver halide emulsion asclaimed in claim 1 wherein the J-band sensitization type dye is selectedfrom dyes represented by the general formula (I), (II), (III), (IV), (V)or (VI):
 3. A photographic silver halide emulsion as claimed in claim 1wherein the amount of silver bromide is from about 15 to about 95 molarpercent.
 4. A photographic silver halide emulsion as claimed in claim 3wherein the amount of silver bromide is from 30 to 90 molar percent. 5.A photographic silver halide emulsion as claimed in claim 1 wherein anaverage particle size, by number, of thE silver halide is less than 0.6Mu .
 6. A photographic silver halide emulsion as claimed in claim 1wherein the silver halide particles are regular.
 7. A photographicsilver halide emulsion as claimed in claim 1 wherein the photographicemulsion is monodispersed.
 8. A photographic silver halide emulsion asclaimed in claim 1 wherein the photographic emulsion further contains awater-soluble type coupler or an oil-protected type coupler.
 9. Aphotographic silver halide emulsion as claimed in claim 1 wherein theJ-band sensitization type dye is selected from the group consisting of10. A photographic silver halide emulsion as claimed in claim 2, whereinsaid substituted alkyl group as represented by R1 and R2 is a memberselected from the group consisting of a hydroxyalkyl group, anacetoxyalkyl group, an alkoxyalkyl group, a carboxy group containing analkyl group, a sulfo group containing an alkyl group, a benzyl group, aphenylethyl group, a p-sulfobenzyl group, a p-carboxybenzyl group, ap-sulfophenethyl group, and an allyl group.
 11. A photographic silverhalide emulsion as claimed in claim 10, wherein said hydroxyalkyl groupis a member selected from the group consisting of a 2-hydroxyethyl groupand a 4-hydroxybutyl group; wherein said acetoxyalkyl group is a memberselected from the group consisting of a 2-acetoxyethyl group and a3-acetoxypropyl group; wherein said alkoxyalkyl group is a memberselected from the group consisting of a 2-methoxyethyl group and a4-butoxybutyl group; wherein said carboxy group containing an alkylgroup is a member selected from the group consisting of a 2-carboxyethylgroup, a 3-carboxypropyl group, and a 2-(2-carboxyethoxy)ethyl; andwherein said sulfo group containing an alkyl group is a member selectedfrom the group consisting of a 2-sulfoethyl group, a 3-sulfopropylgroup, a sulfobutyl group, a 4-sulfobutyl group, a2-hydroxy-1-sulfopropyl group, a 2-(3-sulfopropoxy)ethyl group, a2-acetoxy-1-sulfopropyl group, a 3-methoxy-2(3-sulfopropoxy)propylgroup, a 2-(2-(3-sulfopropoxy)ethoxy)ethyl group, and a2-hydroxy-3-(3''-sulfopropoxy)propyl group.
 12. A method of increasinggreen sensitivity of a photographic silver halide emulsion whichcomprises incorporating in the photographic silver chlorobromideemulsion not prior to the substantial completion of chemical ripening atleast one J-band sensitization type trimethine cyanine dye wherein atleast one of the nitrogen containing heterocyclic nuclei of said dyehas, on the nitrogen atom thereof, a -RCOOH group wherein R is alkylene,or a sulfoalkyl group, and a water soluble iodide in a molar ratio of0.005-0.10 based upon silver chloride which is a component of saidsilver chlorobromide.